A constant-time dynamic storage allocator for real-time systems

  • Authors:

  • Miguel Masmano;Ismael Ripoll;Patricia Balbastre;Alfons Crespo

  • Affiliations:

  • Department of Computer Engineering, Technical University of Valencia, Valencia, Spain 46071;Department of Computer Engineering, Technical University of Valencia, Valencia, Spain 46071;Department of Computer Engineering, Technical University of Valencia, Valencia, Spain 46071;Department of Computer Engineering, Technical University of Valencia, Valencia, Spain 46071

  • Venue:
  • Real-Time Systems
  • Year:
  • 2008

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Abstract

Dynamic memory allocation has been used for decades. However, it has seldom been used in real-time systems since the worst case of spatial and temporal requirements for allocation and deallocation operations is either unbounded or bounded but with a very large bound.In this paper, a new allocator called TLSF (Two Level Segregated Fit) is presented. TLSF is designed and implemented to accommodate real-time constraints. The proposed allocator exhibits time-bounded behaviour, O(1), and maintains a very good execution time. This paper describes in detail the data structures and functions provided by TLSF. We also compare TLSF with a representative set of allocators regarding their temporal cost and fragmentation.Although the paper is mainly focused on timing analysis, a brief study and comparative analysis of fragmentation incurred by the allocators has been also included in order to provide a global view of the behaviour of the allocators.The temporal and spatial results showed that TLSF is also a fast allocator and produces a fragmentation close to that caused by the best existing allocators.